2Mg + O2
2MgO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Starting from the begginning.
We have:
Mg + O2
MgO
Mg2O2 is made from the magnesium and oxygen gas (two at a time), we cancle out the subscripts beacuse they are divisable by the same number ( we can do the same thing, the cancle out I mean, even if they don't go to 1's). Leaveing MgO in this case.
Once again:
Mg + O2
MgO
To balance an equation you have to make sure there are the same number of each element on both sides of the arrow (
).
I found it helpful to write the elemental symbol down for both the right and left side to show how many of each we have.
Like this...
Mg + O2
MgO
Left side:
Mg-1
O-2
Right side:
Mg-1
O-1
=================
Okay, so we should be noticeing that there are a diffrent number of oxygens on both sides. we need to fix that. we need to balance it.
we can add numbers in front of any given element/compound to do so. This number will be multiplied by the entire compound/element (includeing the subscripts). the number can be as large as we want infact.
---
side note
BUT NO ADDING NEW THINGS. like new compounds or elements or combinations or whaterver, just stick to the original equation.
---
we need to give the right side one more oxygen to match up with the left side.
Like so,
Mg + O2
2MgO
So we now have
Left side:
Mg-1
O-2
Right side:
Mg-2
O-2
We now have the same amount of oxygens on both sides. BUT, the magnesiums aren't equaled.
We need 2 on the left side to fix this one.
So we'll add 2 in front of the Mg, on the left side.
Like so,
2Mg + O2
2MgO
And there you have it, a well balanced equation =)
2Mg + O2
2MgO
Left side:
Mg-2
O-2
Right side:
Mg-2
O-2
==============
One last note, you can only have whole numbers when balanceing equations. due to the simple fact that you just can't have half of an atom of something.
So no fractions or decimals when balanceing an equation.
Okay, that should be all you need to work your way through these kinds of problems... at least this one lol
Hope this helps!
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